多级结构微/纳米纤维气凝胶滤料的构建及其过滤机理研究

PM2.5 in the air can be efficiently removed by electrospun nanofiber filter. However, the application of electrospun nanofiber filter was restricted due to its high pressure drop and weak mechanical property. In this study, it was aimed at building high-efficiency and low-resistance air filter and study its filtration mechanism. Firstly, micro/nanofiber will be prepared via electrospinning. Secondly, micro/nanofiber aerogels will be constructed through three-dimensional network reconstruction method and solvent fumigation reinforcement method. Thirdly, silica nano filaments will be deposited on the surface of fibers in aerogels. Ultimately, a micro/nanofiber aerogels filter with hierarchical structure will be constructed. The three-dimensional spatial distribution characteristics of hierarchical pore structure will be studied. The relationship between multi-fiber components and the mechanical properties of the filter media will be studied. Thus the forming mechanism of hierarchical structure in micro/nanofiber aerogels and the functional mechanism between structure and performance will be revealed. Further more, via testing and analyzing the filtration performance of the micro/nanofiber aerogels filter media, the structure-activity relationship between hierarchical structure and filtration performance will be studied. And a mathematical model of micro/nanofiber aerogels filter will be established, simulating the flow characteristics of the gas flow and the filtration characteristics of the particles in the aerogels filter. The filtration mechanism and structure-activity relationship of the hierarchical micro/nanofiber aerogels filter will be clarified. This subject will provide theoretical support for the construction of hierarchically structural micro/nanofiber aerogels and the study of filtration mechanism of hierarchical structural filter.

静电纺纳米纤维能够高效清除空气中的PM2.5，然而较高的滤阻和脆弱的力学性能限制了其应用，因此利用静电纺纳米纤维构建高效低阻型滤料仍面临巨大挑战。本项目以构建高效低阻空气滤料并明确其过滤机理为目标，首先以静电纺丝法制备微/纳米纤维，其次通过三维网络重构法与溶剂熏蒸加固法构筑气凝胶，然后采用表面沉积技术在气凝胶纤维表面沉积二氧化硅纳米线，构建具有多级结构的微/纳米纤维气凝胶滤料。研究多级孔结构的三维空间分布特征，明确多纤维组分与滤料物理性能的作用机制，并进一步揭示多级结构微/纳米纤维气凝胶的成型机理及结构与性能作用机制；测试微/纳米纤维气凝胶的过滤性能，研究多级结构与过滤性能之间的影响机制，建立数学模型并模拟气流流动特性和颗粒物的过滤特性，阐明多级结构微/纳米纤维气凝胶滤料过滤机理及其构效关系。该项目的研究将为多级结构微/纳米纤维气凝胶滤料的构建和多级结构滤料过滤机理的研究提供理论支撑。

背景：研发应用于环境治理的的过滤与分离材料并解决其制备关键技术，是我国环保领域的研究重点和热点。传统的过滤与分离材料结构致密而导致过滤与分离阻力较大，难以实现高效低阻。.主要研究内容：本课题针对目前高效过滤与分离材料存在的缺陷与不足，通过三维网络重构法，结合纳米二级结构改性技术，构建了仿生三维多级结构微/纳米纤维气凝胶基过滤与分离材料，并系统的研究了仿生三维多级结构微/纳米纤维气凝胶基过滤与分离材料的理/化结构与过滤分离性能间的构效关系，在此基础上提出了三维多级网络结构提升材料过滤与分离性能的机理。.重要结果：采用三维网络重构法，以PI纳米纤维为原料，通过冷冻-干燥并结合溶剂蒸气熏蒸加固技术，成功开发出结构可调控、性能理想的高回弹聚酰亚胺纳米纤维气凝胶(PI-NFAs)。通过液相沉积的方法，在聚酰亚胺纳米纤维表面沉积低表面能硅纳米线(SiNFs)，并结合纳米纤维气凝胶的类蜂窝状多级孔网络结构形态，构筑了具有微/纳米双阶粗糙结构的超疏水-超亲油聚酰亚胺纳米纤维气凝胶(SiNFs/PI-NFAs)。将PI纳米短纤维与PI针刺非织造基材进行复合，制备微/纳米纤维气凝胶基高温烟气过滤材料(PI-M/NFAs)。.关键数据：通过调控分散液中纤维固含量，制备的气凝胶密度在0.58~15.76 mg/cm3、孔隙率在98.99 ~ 99.96%范围内。仅在液体自身重力驱动作用下，SiNFs/PI-NFA12基于尺寸筛分表面过滤，并结合聚结分离，通过众多曲折微通道中的液滴聚结拦截乳化液滴，对各种油/水混合物的水截留率最高可接近100%同时保持较高的油通量(7.5×104~1.2×105 Lm-2h-1)，也证实了SiNFs/PI-NFA12对粘度较大的油也具有较高的分离效率。.科学意义：该研究为纳米纤维气凝胶在过滤与分离领域的应用和开发“高效低阻”型过滤与分离材料提供了一定的理论指导和借鉴意义。